part of develops from spermatozoon pre-blastoderm embryo sperm derived structure fly_anatomy.ontology The sperm flagellum structures, which are composed of proteins and mitochondrial derivatives. They are observed in the embryo cytoplasm shortly after fertilization. By cellular blastoderm stage these structures are observed in the yolk cytoplasm where they remain until the formation of the embryonic digestive tract. After larval hatching they are observed in the midgut, and shortly after excreted through defecation. FBbt:00005809 cell component